After all, RIM's greatest strength is a killer email-application for BlackBerrys. Why didn't it have email baked into the PlayBook?

Turns out it had to skip native email support on the PlayBook because its architecture can't support two devices with one person's account, according to a source.

Here's how our source explains it: "The Blackberry email system is the BES -- which is the source/focus of all the famous BB security. The BES email server has the concept of one user = one device (or they call it PIN)."

When RIM built its system it didn't see ahead to realize there would be a time when a user could have a smartphone and a tablet. So now it has "significant work to make the BES support multiple devices."

RIM should be able to rearchitect its system, but our source points out, it's "a lot of work to change something that's pretty basic in the software architecture and design."

And it's indicative of the turnaround project RIM has on its hands. It's trying to switch from its current platform to a new platform, QNX. That's no easy task.

Our source learned about the PlayBook problems from a director of product management at BlackBerry World, its big developer conference and reached out after reading some of our stories about what's happening inside the company.

Now, this is just one guy, so take it with a grain of salt, but it seems to match with this Crackberry explanation which says RIM intentionally skipped implementation of email to make sure it worked with its internal system.

RIM is expected to offer native email support for the PlayBook this summer. It will be an interesting test to see how well it can adjust its system.